Heterophyiid parasites are trematodes found in many species of fish, often in the muscles where they can be eaten by humans. Reports that up to 14% of myocarditis in the Phillipines may be due to heterophyiid infection led us to attempt to document this little-known phenomenon in a rhesus monkey model using Phagicola nana, a parasite of local sunfish and bass. Viable metacercariae were given to a monkey per os via stomach tube, and the infection followed by daily stool examination and periodic electrocardiograms. The parasite was able to establish itself in the monkey and eggs were passed in the stool. When the monkey was necropsied for other reasons we were able to examine all tissues for evidence of eggs. No eggs were found in extraintestinal tissue and no clinical manifestations of the infection, as reflected by electrocardiogram, were noted. This is the first report of P. nana infection in a primate species and shows the potential for human infection in Louisiana, although the potential for this parasite to contribute to cardiomyopathy was not demonstrated.